1. Field of the Invention
This invention relates generally to a toy helicopter, and pertains more specifically to a toy helicopter having a rotor that, once actuated, gradually accelerates to simulate the start-up of a full-scale helicopter. In the preferred embodiment, rotational acceleration of the rotor is induced by frictional interaction between the surface of a tubular drive shaft and the surface of a bore formed in the rotor hub. Actuation of the toy is accomplished by the simple lifting of an actuating shaft which extends from the rotor hub and from within the tubular drive shaft. The toy is deactivated by allowing the actuating shaft to return to its rest position, such as by placing the toy on a horizontal surface.
The toy helicopter of the present invention also incorporates a flashing light mechanism to further simulate the operation of a full-scale helicopter. The light flashes in time with the rotation of the drive shaft, thereby recreating the lighting effect associated with full-scale helicopters. Another feature of the present invention is an audio mechanism which imparts a sound which simulates that of a full-scale helicopter in operation.
2. Description of the Prior Art
Children prefer toys that are both realistic and fun to operate. To satisfy this preference, toy makers expend great effort to simulate in their miniature replicas the features of the full-scale items they depict. For example, miniature automobiles will frequently depict in substantial detail various miniature automotive components such as the steering wheel, transmission and exhaust systems.
In the past, various toy helicopters have been devised for use by children. Most of these toys embody some of the features of the full-scale helicopters they depict. The degree of entertainment provided by these toys is directly related to the realism evoked by their features and operation. One such feature involves the start-up of the toy helicopter, which in the full-scale item constitutes a gradual buildup of rotational velocity of the rotor. To simulate this type of start-up in a miniature toy replica, one must likewise provide a way to gradually induce acceleration of the toy's rotor. However, providing such realistic start-up in a toy increases the complexity of the design and hence the cost to manufacture the toy and, moreover, may detract from the toy's ease of operation.
A conventional toy helicopter is depicted in Shapiro et al. U.S. Pat. No. 2,411,596. In this patent, the rotor is rotated by a drive shaft that is rigidly affixed to the rotor. Thus, a gradual increase in rotor speed during start-up is not provided in the Shapiro et al. design, and the design therefore lacks an important aspect of realism.
In Robbins et al. U.S. Pat. No. 3,093,929, a toy helicopter design is provided which employs belts to transmit rotary movement to two rotor shafts. However, the patent contains no teaching that gradual acceleration of the rotors is even possible using its belt-driven design.
In Cohn U.S. Pat. No. 2,732,656, a toy helicopter is described in which a coil spring is used to transmit rotational movement from the shaft of a hand-wound motor to a rotor shaft. While the Cohn patent states that the coil spring is in frictional engagement with both shafts, there is no suggestion or teaching that gradual acceleration of the rotor can be accomplished using its slipping spring design.
The present invention is directed to overcoming the lack of realism inherent in the prior art. In the present invention, a toy helicopter is provided in which gradual acceleration of the rotor during start-up is achieved to provide a realistic simulation of the start-up of a full-scale helicopter. The toy is actuated by simply lifting a shaft extending from the rotor hub. A flashing light mechanism and an audio mechanism enhance the realism to the toy. The present invention accomplishes these goals through a safe, simple design adapted for high speed, low cost manufacture.